Examination strategies of experienced and novice clinicians viewing the retina

Purpose: Expertise in viewing medical images is thought to be due to the ability to process holistic image information. Eye care clinicians can inspect photographs of the retina to search for signs of disease. However, they commonly also view the eye in vivo using the restricted view of a slit lamp, which removes the potential benefits of holistic processing. We investigated how expert and novice clinicians inspect the fundus using these two methods. Methods: Twenty clinicians (10 experienced, 10 novices) examined 64 photographs of human retinae. Each participant viewed half of the images as fundus photographs while having their eye position recorded. The other half were viewed via a simple slit lamp simulation, whereby a computer mouse was used to control the position of a viewing window that revealed the underlying fundus photograph. Results: Experienced clinicians made decisions significantly faster than novices, with faster decision-making when viewing the fundus photograph compared to via the slit lamp simulation. The distribution of inspection was similar, although novices spent longer examining the optic nerve head than other regions. Experienced clinicians showed significantly earlier inspection of the optic nerve head when it was judged to be unhealthy. Conclusions: Our results support the idea that experienced eyecare clinicians use holistic image information, if available, when inspecting the fundus. This was particularly prominent for the optic nerve head region, which was the region that novices spent most of their time examining. Holistic processing benefits were only present in experts' free-viewing fundus photographs; the limited field of view from the slit lamp disrupts such global image benefits.